Displayed images (e.g., slides) projected onto a display screen or display area are often used during an oral presentation. The displayed images serve to enhance or supplement the oral portion of the presentation. Often the image data for driving a display device for displaying the images is provided by a computer system. Commonly, specific software applications are run by the computer system (e.g., slide generation software application) to generate the image data to be displayed by the display device.
FIG. 1 shows an example of a prior art computer controlled display system including a computer system 10 for providing image data 10A for driving a display device 11 to project an image (designated by dashed lines 11A and 11B) on a display area 12.
In this type of system, a presenter commonly uses a pointing device such as a light or laser pointer 15 to project a light or laser signal toward the displayed image thereby projecting a single light point onto the displayed images. Typically, the purpose of the projected point is to bring the audience's attention to a particular location on the displayed image. In addition to the laser pointer 15, the presenter often uses an input device 14 such as a mouse to control the computer system generating the image data 10A and more specifically, to control the manner in which the image data is displayed. Commonly the input device is a remote mouse that transmits control signals via infrared optical signals to change from one displayed slide to the next.
In one known technique, the display system further includes an image capture device 13 that captures the displayed image (designated by dashed lines 13A and 13B) and any object projected on or positioned in front of the displayed image. The captured data 13C is provided to an image analyzer 16 that determines the location of the objects and provides this location information 16A to the computer system 10. Providing the location information of objects, such as pointing sticks, fingers, or light pointers, to the computer system can provide a user the ability to interact with the displayed image using these pointing devices.
However, detection of an object used for pointing (e.g., a wooden stick or a finger) positioned in front of a displayed image using the system shown in FIG. 1 is more reliable than detection of a light point projected on the displayed image. Specifically, in the case of detecting an object, a technique is known using the system shown in FIG. 1 that reliably detects the pixel locations of the object in the captured image data by separating foreground image data from the displayed image data within the captured image data. However, it is often difficult to determine whether the detected pixels using this technique correspond to a laser point or if the detected pixels are produced by a noisy system or environment. The main reason for this is because a laser point tends to cover only a few pixels locations within the captured image data in the same way as noise manifests itself. This problem of detecting the laser point can be further exacerbated by poor lighting conditions, inferior image capture or display devices, or a highly dynamic image.
In another known technique, the chromatic nature of the laser pointer (i.e., typically a single highly saturated color) is used to detect a laser point within captured image data by detecting pixel values have an anticipated specific color and intensity that is unlike the displayed image data 10A. However, manufacturing variations can affect the laser pointer intensity and as a result, detection relying on an anticipated laser intensity may be problematic.
Hence, what would be desirable is a system and method for reliably detecting a light point on a computer controlled displayed image.